Radio audio volume spikes on Newstalk 106 (seems more frequent in rain)?!

[outofbandii]

Looking for some help or advice with what's becoming a stranger and stranger audio problem. The issue is the radio volume is spiking up to very loud at times.

Example linked below. Be warned, the audio spikes loud in spots, I've reduced the gain on this clip but check you don't have speakers up loud before playing.

https://soundcloud.com/alastairmcder...-volume-spikes

This is the BMW Business Radio in my 2002 E39 525i. The radio volume spikes at times as can be heard in this clip. This is a particularly bad instance of it happening - normally it happens less frequently (once every 10-20 mins). I was doing some testing and subjected myself to the horror of listening to 2FM for 15 minutes - no volume spikes. So it's only happening on Newstalk106 so far. Haven't tested on other frequencies yet

There is a Dension bluetooth unit installed (the blue Gateway Lite BT) in the glovebox wired in by a previous owner. The FM radio channel audio spike can be heard when the radio is in both normal radio mode and in CD mode (while playing bluetooth audio it cuts in about 0.5s of very loud audio from the radio channel).

Anyone know what the problem might be? I was wondering about loose wires and checked the Dension unit - snug fit for input cable. The other thing that could be related or just coincidental is weather - it was really bad when heavily overcast with solid rain when I recorded the above, this is significantly more frequent than normal.

Any ICE or physics experts who can explain what's going on here?

[dergside]

That does sound strange.

There is a speed sensitive volume setting that raises/lowers the volume as speed goes up or down. The setting of that is done through the Bass/Treble, etc. button and the values it can be set at are 1-5. Usually 3 or 4 seems to work but I don't think there is any other adjustment for weather conditions (unless you have auto wipers and they have a feature I wasn't aware of).

[alan996]

Curious about this too as I've had it happen a few times in my e70 with radio 1

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[318is-joe]

I had it on a previous E39, it would spike and then disappear. Turned out it was the volume potentiometer, if I wiggled the knob it would come in and out - was worse on a damp day.
Tried to source a potentiometer, but couldn;t find now anywhere with an integral push for on/off.
Ended up replacing the head unit

[alan996]

But for me it's only one one radio station and nothing else

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[Dave]

It may not be a problem with your car, Newstalk share an antenna system on Mount Leinster with us, we're having problems with the antenna system.

Newstalk are running reduced Power on 107.2, we're also running reduced Power on 102.0, what you may be hearing is your RDS jumping between frequencies with different Mod levels.

We thought we found the problem this morning, it looked like water ingress.

This is the feeder cable


The dipole


Everything tested fine but after an hour our SWR went through the roof.

It looks like we're gonna need to replace the entire antenna system, which is a bummer.


But what a day!



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[HealyC]

It may not be a problem with your car, Newstalk share an antenna system on Mount Leinster with us, we're having problems with the antenna system.

Newstalk are running reduced Power on 107.2, we're also running reduced Power on 102.0, what you may be hearing is your RDS jumping between frequencies with different Mod levels.

We thought we found the problem this morning, it looked like water ingress.

This is the feeder cable


The dipole


Everything tested fine but after an hour our SWR went through the roof.

It looks like we're gonna need to replace the entire antenna system, which is a bummer.


But what a day!



Sent from my iPhone using Tapatalk Pro

Fork me Dave, wasn't expecting that reply!

Try Newstalk on another frequency, don't know where you are but in Dubland you'll get it on 106.0 and 107.4/.6


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[Dave]

Fork me Dave, wasn't expecting that reply!

Try Newstalk on another frequency, don't know where you are but in Dubland you'll get it on 106.0 and 107.4/.6


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Lol, it's not often I get to talk about work

If the issue started about 2 weeks ago, it's probably the transmission problem.


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[318is-joe]

Well that was an unexpected reply lol - OP, if it's only on a single channel it's deffo not what I suggested lol, but can you disable rds etc and see how it goes

[outofbandii]

Thanks for all the replies folks. I certainly didn't expect Dave's post, very cool pic - hope you got the problem sorted.

This colume spike issue is kinda weird to diagnose because I think I'm seeing conflicting symptoms - it certainly does appear to be worse when it's damp, but it also only appears to be happening with Newstalk. Maybe it's just that I was listening to Newstalk when it was raining, I need to test other stations next time it's happening again (but it's never been as severe as in that recording). Another thing to mention on it being station specific is that I'm usually in Mayo, but I also see this issue when back in Dublin.

I was watching and noticed that when the volume spike hits during bluetooth play, the radio display text changes from "CD 5-01" (or whatever track number it happens to be on) to "106.8 FM". It just changes for that split second during the spike, and then changes back to CD mode (which the Dension unit uses for bluetooth).

Are these conflicting symptoms of potentiator vs some kind of radio frequency or RDS?

I'm going to try disabling RDS and see if that helps.